Field of the Disclosure
The present disclosure relates generally to wireless communication systems and, more particularly, to licensed and unlicensed frequency bands in wireless communication systems.
Description of the Related Art
The demand for mobile wireless data has been growing at an exponential rate and is expected to continue to grow by many orders of magnitude in the coming years. Meeting the increasing demand will require a corresponding increase in the amount of spectrum available for wireless communication. The available spectrum can be increased by combining licensed frequency bands with unlicensed frequency bands. Unlicensed frequency bands are portions of the radiofrequency spectrum that do not require a license for use and may therefore be used by any device to transmit or receive radio frequency signals. For example, the Unlicensed National Information Infrastructure (UNII) is formed of portions of the radio spectrum that include frequency bands in the range of 5.15 GHz to 5.825 GHz such as the U-NII-1 band in the range 5.15-5.25 GHz, the U-NII 2a, b, c bands in the range 5.25-5.725 GHz, and the U-NII 3 band in the range 5.725-5.825 GHz. Unlicensed frequency bands can be contrasted to licensed frequency bands that are licensed to a particular service provider and may only be used for wireless communication that is authorized by the service provider. Different radio access technologies (RATs) may share portions of the unlicensed frequency bands. For example, radios that operate according to Long Term Evolution (LTE) standards defined by the Third Generation Partnership Project (3GPP) may share portions of the 5 GHz unlicensed frequency band with Wi-Fi radios that operate according to 802.11 standards defined by the Institute of Electronics and Electrical Engineers (IEEE).